On Thu, Sep 16th, 2010 at 9:27 AM, dale mcinnes <wdm1949@hotmail.com> wrote:
> If sexual behavior is at the root cause of the elongation of spine growth
> then,
> why DON'T we see more of this in other clades?? This should be occurring
> everywhere
> since sexual selection is also everywhere in every clade and NOT dependent on
> envir-
> onmental regimens.
There are numerous reasons why neural spine elongation wasn't always the
'sexiness of choice':
1) Not all species may have used visual displays to attract mates. Some may
have used scent,
song, or courtship 'dances'. Sometimes all you need to get the girls is to be
able to kick your
opponents' arses in intraspecific combat - where in fact a lack of impeding
adornments might even
be an advantage.
2) Of those that used visual displays, bright colouration may have been
preferable to changes in
body form. Perhaps those species that resorted to costly changes in body form
simply lacked the
genetic resources to evolve bright colours or bold markings.
3) Elongated neural spines may have been just one type of display structure.
Crests, frills, horns,
spikes and plates may have also been primarily for display purposes in some
species.
--
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Dann Pigdon
Spatial Data Analyst Australian Dinosaurs
Melbourne, Australia http://home.alphalink.com.au/~dannj
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